With the desire to improve passenger safety and fuel efficiency, Ultra High Strength Steels (UHSS) have been developed for use in the automotive industry. UHSS are high strength steels with high ductility and strength. DP 980 is one of these UHSS being applied in automobile manufacturing. DP 980 is difficult to join with Resistance Spot Welding (RSW) because of the high carbon content and alloying in this material. The weld becomes brittle when it solidifies during the welding process. With the desire and motivation of widely using UHSS, new welding processes are needed to be developed in order to effectively join DP 980. Friction Stir Spot Welding (FSSW) is a developing welding process aimed to replace RSW in the automotive industry because of its ability to join materials at a lower temperature. Currently the welding loads of the tools are higher than 2000 pounds, ranging from 3,000 to 5,000 pounds, which exceeds the limit of the welding robots in the automotive factories. It is proposed that the welding loads can be reduced by increasing the spindle speed of the FSSW tool. Other focuses in the research include increasing the life of the tool and developing acceptable welding parameters for High Speed FSSW. The experimental work done for this thesis provided support that weld strength can be obtained at levels above the acceptable standard for DP 980 material (greater than 2400 pound lap shear fracture load for 1.2 mm material) while keeping the vertical load on the welding machine spindle below 2000 lbs.

In the last two decades or so, hybrid structures from dissimilar materials and/or sheet gauges have been developed to achieve weight reduction while maintaining or even improving structural performance such as stiffness, crash and impact behavior. In particular, welded and brazed sheet materials in the form of tailor blanks (TBs) are being increasingly used or considered for future applications in different applications such as automotive, aerospace and marine constructions as they offer attractive combination of strength and performance in applications where weight reduction is desirable. However, technical problems are often encountered during forming of TBs from dissimilar base sheet materials with different thickness and/or strength. These include weld line movement and non-uniform deformation. Additionally, there are premature weld failures due to the presence of softening zone (as in TBs made from advanced high strength steels), and brazed interface failure due to insufficient bonding and wetting (as in TBs made from steel and aluminum). These areas of forming of TBs need to be scientifically studied to advance the use of dissimilar materials. The current research involves an understanding of deformation and forming behavior of steel-to-steel tailor welded blanks (TWBs) made from advanced high strength steel (AHSS) such as dual phase (DP780) steel. The research also involves a study of deformation behavior of steel-to-aluminum tailor brazed blanks (TBBs). TWBs have been successfully joined using a relatively new welding techniques such as defocused fiber laser welding. TBBs, on the other hand, have been successfully produced by fiber Laser/MIG hybrid brazing and Cold Metal Transfer brazing (CMT). In addition, the formability of TWBs of different gauges and/or strengths was tested by using a new, simple and reproducible method of formability testing using a double-layer blank method. This method was devised and assessed for testing various steel combinations in different strain paths such that the weld line stayed in position with respect to forming tools and is subjected to the same stress and strain state as the parent material in the weld and its vicinity. Moreover, results from conventional stretch forming tests, single-layer blank, and the double-layer method were compared at the macroscopic level (such as weld line movement, forming limit etc.) as well as at the microscopic level (such as failure location within the weld and failure mode) to isolate the advantages of the proposed double-layer method. With regard to TBBs made by fiber Laser/MIG and CMT brazing methods, a fundamental knowledge and understanding of the local deformation behavior and material plastic ow in and around the brazed steel-aluminum interfaces were obtained by conducting miniature tensile mechanical tests that focus on continuous observation of the brazed region under a high magnification optical microscope to assess the ductility of the brazed joint and its capacity to carry the load during a material shaping process. / Thesis / Doctor of Philosophy (PhD) / In the last two decades or so, hybrid structures from dissimilar materials and/or sheet gauges have been developed to achieve weight reduction while maintaining or even improving structural performance such as stiffness, crash and impact behavior. In particular, welded and brazed sheet materials in the form of tailor blanks (TBs) are being increasingly used or considered for future applications in different applications such as automotive, aerospace and marine constructions as they offer attractive combination of strength and performance in applications where weight reduction is desirable. However, technical problems are often encountered during forming of TBs from dissimilar base sheet materials with different thickness and/or strength. These include weld line movement and non-uniform deformation. Additionally, there are premature weld failures due to the presence of softening zone (as in TBs made from advanced high strength steels), and brazed interface failure due to insufficient bonding and wetting (as in TBs made from steel and aluminum). These areas of forming of TBs need to be scientifically studied to advance the use of dissimilar materials.

The transcription factor Krüppel homolog 1 (Kr-h1) is crucial in multiple reproductive processes of Aedes aegypti mosquitoes, including previtellogenesis, vitellogenesis, and oogenesis. This study explores the interaction between Kr-h1 and its potential associated proteins (KAPs), with a specific focus on the dimerization partner (DP-1), and how this interaction regulates gene expression pathways critical for mosquito reproduction. Utilizing RNA interference (RNAi), the research identifies DP-1 as a significant regulator of follicle growth post-eclosion (PE), highlighting its vital role in the mosquito reproductive regulatory pathway. The experimental approach included RNAi-mediated knockdown of DP-1, accompanied by evaluations using quantitative PCR (qPCR), Western blotting (WB), co-immunoprecipitation (Co-IP), follicle length measurement, and egg counting to assess the role of DP-1 in reproductive functions. For the first time, the inhibition of DP-1 expression was found to significantly impede A. aegypti follicular development. The elucidation of the mechanistic roles of Kr-h1 and DP-1 provides valuable insights that could lead to innovative strategies for mosquito population control and effective disease vector management. / Master of Science in Life Sciences / Mosquitoes can spread serious insect-borne diseases such as dengue, Zika, and malaria, etc. These diseases can infect hundreds of millions of individual and cause around a million of death annually. This study focuses on a specific mosquito species, Aedes aegypti, which is a major carrier of these diseases. To manage their populations and reduce the spread of these diseases, scientists are constantly seeking new methods to control their reproduction. Chemical insecticides are one of the most efficient and widely used strategies. However, these insecticides face significant challenges, including the development of resistance in mosquito populations and the potential damage to non-target species to affect the ecosystem. To address this issue, the development of new insecticides is crucial. We can identify new targets to pave the way to research novel effective insecticides. Inside mosquitoes, there are various proteins that help control their ability to reproduce. One of these proteins is called Krüppel homolog 1 (Kr-h1). Kr-h1 plays a crucial role in the development and reproductive processes of mosquitoes. Our research looked at how Kr-h1 interacts with other types of protein to control mosquito reproduction. Through various experiments, including gene expression analysis and protein studies, we found that DP-1 is essential for the proper development of mosquito eggs. This insight helps us understand more about the biological processes and hormonal pathways during mosquito reproduction, therefore provide greater opportunity to develop insecticides to reduce their populations and the spread of the diseases they carry.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The necessity to acquire and analyze data dates back to the beginning of science itself. Long ago, a scientist may have run experiments and noted the results on a piece of paper. These notes became the data. The method was crude, but effective. As experiments got more complex, the need for better methodologies arose. Scientists began using computers to gather, analyze, and store the data. This method worked well for most types of data acquisition. As the amount of data being collected increased, larger computers, faster processors, and faster storage devices were used in order to keep up with the demand. This method was more refined, but still did not meet the needs of the scientific community. Requirements began to change in the data acquisition arena. More people wanted access to the data in real time. Companies producing large data acquisition systems began to move toward a network-based solution. This architecture featured a specialized computer called the server, which contained all of the data acquisition hardware. The server handled requests from multiple clients and handled the data flow to the network, data displays, and the archive medium. While this solution worked well to satisfy most requirements, it fell short in meeting others. The ability to have multiple computers working together across a local or wide area network (LAN or WAN) was not addressed. In addition, this architecture inherently had a single point of failure. If the server machine went down, all data from all sources was lost. Today, we see that the requirements for data acquisition systems include features only dreamed of five years ago. These new systems are linked around the world by wide area networks. They may include code to command satellites or handle 250 Mbps download rates. They must produce data for dozens of users at once, be customizable by the end user, and they must run on personal computers (PCs)! Systems like these cannot work using the traditional client/server model of the past. The data acquisition industry demands systems with far more features than were traditionally available. These systems must provide more reliability and interoperability, and be available at a fraction of the cost. To this end, we must use commercial-off-the-shelf (COTS) computers that operate faster than the mainframe computers of only a decade ago. These computers must run software that is smart, reliable, scalable, and easy to use. All of these requirements can be met by a network of PCs running the Windows NT operating system.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Les études sur les procédés de soudage et sur la fiabilité des structures assemblées apparaissent actuellement comme un domaine de recherche actif, ouvert et complexe, car elles nécessitent de combiner de nombreuses connaissances dans différents domaines de la physique, de la mécanique et des procédés. La distribution des contraintes résiduelles joue un rôle important dans la vie des structures en favorisant la rupture par fatigue ou par fissuration. Ainsi, une meilleure compréhension des contraintes résiduelles évite l'utilisation de facteurs de sécurité plus élevés et, par conséquent permet de mieux optimiser le cycle de vie des structures soudées. A travers ce travail de thèse, nous nous sommes intéressés au soudage par laser d’un acier dual phase DP600, soudé en configuration par recouvrement, dont l’application est l’utilisation dans le domaine automobile. Cette thèse présente deux volets : un volet expérimental et un volet numérique.L’étude expérimentale nous a permis d’une part d’appréhender les conséquences métallurgiques et mécaniques du procédé laser sur l’acier DP600 et d’autre part d’utiliser et de valider les résultats numériques des modèles développés. L’étude numérique a eu pour objectif de prédire l’histoire thermique, métallurgique et l’évolution des caractéristiques mécaniques des tôles soudées par faisceau laser. Nous avons développé, sur un code de calcul par élémentsfinis Abaqus, trois modèles numériques. Le modèle thermomécanique, nous a permis de simuler la distribution spatio-temporelle de la température. Dans ce cas, le chargement appliqué est dépendant des paramètres du procédé etdes caractéristiques du faisceau laser et est associé à des conditions aux limites. Pour le modèle mécanique, nous avonsconsidéré un comportement élasto-plastique avec un chargement thermique transitoire, résultat du modèle thermique.Le deuxième modèle thermo-métallurgique nous a permis de simuler les phénomènes d’austénisation pendant la phase de chauffage (modèle de Waeckel) et de prendre en compte les fractions volumiques des phases martensitiques générées par les transformations de phases austénite–martensite lors du refroidissement (modèle de Koistinen-Marburger). Enfin, dans la dernière partie de simulation, nous avons réalisé le couplage thermo-metallo-mécanique. Les résultats obtenus dans la partie précédente, ont été implémentés dans deux modèles mécaniques : le modèle mécanique classique et le modèle mécanique avec prise en compte de la déformation liée aux effets de dilatation métallurgique. Cet effet a été intégré à travers le coefficient de dilatation thermique des phases ferritiques et martensitiques et des fractions volumiques obtenues à partir du modèle thermo-métallurgique. Les résultats ont montré que la répartition des contraintes résiduelles dans la zone de fusion et dans la zone affectée thermiquement sous l’effet de la déformation thermo-métallurgique donne des valeurs supérieures à celles estimées par le modèle élasto-plastique classique. / Studies on welding processes and the reliability of assembled structures currently appear as an area of active research, open and complex as they need to combine knowledge in many different fields of physics, mechanics and processes. The distribution of residual stress plays an important role in the life of welded structures by promoting fatigue failure or cracking. Thus, a better understanding of residual stress avoids the use of higher safety factors and therefore helps to optimize the life cycle of welded structures. Through this work, we are interested in laser welding of steel DP600 dual phase welded overlap configuration, the application is the use in the automotive field. This thesis has two components: an experimental and a numerical part. The experimental study allowed us, firstly to understand the metallurgical and mechanical effects of laser welding on steel DP600 and secondly to use and validate the numerical results of the developed models. The numerical study aimed to predict the thermal history, and metallurgical changes in mechanical properties of laser beam welded sheets. We have developed three numerical models by using a finite element code inside Abaqus. The thermomechanical model allowed us to simulate the temporal and spatial distribution of temperature. In this case, the applied load is dependent on the processing parameters and characteristics of the laser beam and is associated with boundary conditions. For the mechanical model, we considered an elastoplastic behavior with a transient thermal loading result of the thermal model. The second thermo-metallurgical m odel allowed us to simulate the phenomena austenitizing during the heating phase (Waeckel model) and take into account the volume fraction of martensitic phase transformations generated by the austenite-martensite transformation during cooling (Koistinen-Marburger model). Finally, in the last part of simulation, we have achieved the metallothermo- mechanical coupling. The results obtained in the previous section have been implemented in two mechanical models: the classical mechanics model and the mechanical model taking intoaccount the deformation due to the effects of metallurgical expansion. This effect has been built through the coefficient ofthermal expansion of ferritic and martensitic phases and volume fractions obtained from the thermo-metallurgical model. The results showed that the distribution of residual stresses in the fusion zone and the heat affected as a result of the eformation thermometallurgical field gives values higher than those estimated by the classical elastic-plastic model.

In vielen Staaten unterscheidet sich die Leistung von Schülern mit und ohne Migrationshintergrund. Schüler mit Migrationshintergrund sprechen eine Minderheitensprache sowie die Zielsprache des Wohnlandes, das führt zu einem gewissen Grad der Zweisprachigkeit. Die Zweisprachigkeit ist mit Entwicklungsmustern verbunden, die das Fremdsprachenlernen der bilingualen Schüler positiv beeinflussen können. Diese Dissertation untersucht die Beziehung zwischen Zweisprachigkeit und Fremdsprachenlernen. Die erste Studie untersuchte die Wirkung der Zweisprachigkeit von Schülern mit Migrationshintergrund auf das Erlernen von Englisch als Fremdsprache. Die Ergebnisse zeigen einen positiven Trend zwischen Zweisprachigkeit und Lernerfolg. Dieser Trend unterschied sich deutlich zwischen Gruppen verschiedener Heimatsprachen mit den Kenntnissen der Unterrichtssprache als stärksten Prädiktor. Die zweite Studie betrachtete die Wirkung von Zweisprachigkeit auf die Leistung in Englisch als Fremdsprache von der Grundschule bis zur weiterführenden Schule. Die Analysen zeigen, dass, ein wesentlicher Vorteil der Zweisprachigkeit in der Grundschule vorliegt, dieser aber in der Sekundarstufe I verschwindet. Dies führt zu unterschiedlichem Leistungszuwachs von zweisprachigen und einsprachigen Schülern. Die dritte Studie untersuchte die Wirkung der Zweisprachigkeit auf das Erlernen von Englisch als Fremdsprache unter Berücksichtigung der Auswirkungen von Methode und Abfolge des Erlernens der Zweitsprache sowie des Sprachgebrauchs. Die Ergebnisse zeigen Leistungsvorsprünge in der Drittsprache für Zweisprachige, die in ihrer Minderheitensprache unterrichtet werden, beide Sprachen simultan erwerben und häufiger zwischen beiden Sprachen wechseln. Diese Dissertation gibt weitere Hinweise darauf, dass unter bestimmten Voraussetzungen Zweisprachige mit Migrationshintergrund im Vergleich zu einsprachigen Schülern Vorteile im Fremdsprachenlernen haben, obwohl sich dieser Befund im Laufe der Zeit verändert. / There is a large achievement gap between students with immigrant background and their peers. Many students with immigrant backgrounds speak a minority language at home as well as the majority language of the larger society, resulting in some level of bilingualism. Bilingualism is associated with unique patterns of development that may affect their foreign language learning (FLL) in positive ways. This thesis explores the relationship between bilingualism and FLL, focusing on factors that affect this relationship. The first study investigates the effect of immigrant bilingualism on English FLL, examining confounding background variables and the effect of instructional language proficiency. The results showed a general positive trend between bilingualism and FLL. This positive trend differed between bilingual groups with different home languages with the strongest predictor for FLL being instructional language proficiency. This second study considers the effect of bilingualism on the FLL from elementary to secondary school. Although a significant advantage of bilingualism is found in elementary school, it disappeared as students proceed into secondary school, yielding differential gains for the language minority and monolingual groups. The level of exposure to the minority language played an important role for the FLL development. The third study examines the effect of bilingualism on FLL, considering the impact of manner and age of bilingual acquisition as well as language use practices. The results showed higher FLL for bilinguals who received formal instruction in their minority language, had acquired both languages simultaneously, and switched more often between their two languages, when compared to their other bilingual and monolingual peers. The findings of this thesis add to the evidence that under certain conditions, some bilinguals from immigrant communities have advantages in FLL compared to their monolingual peers although this pattern does change over time.

Frühe mathematische Bildung ist in den vergangenen Jahren verstärkt auch zum Gegenstand der fachdidaktischen Forschung geworden. Ob frühpädagogische Fachkräfte im Rahmen ihrer Ausbildung oder beruflichen Praxis die zur Begleitung früher mathematischer Bildung erforderliche Kompetenz erwerben, wurde erst in den vergangenen sechs Jahren verstärkt empirisch untersucht. Nach wie vor können große Forschungsdesiderate identifiziert werden. Mit der vorliegenden kumulativen Dissertation wird ein Beitrag zur Schließung der Forschungslücken geleistet. Das Hauptziel der Arbeit ist die Analyse der Kompetenzstruktur angehender frühpädagogischer Fachkräfte im Bereich Mathematik unter Berücksichtigung von Dispositionen und situationsspezifischen Fähigkeiten. Damit verbunden sind die Entwicklung eines videobasierten Instruments zur Erfassung der situationsspezifischen Fähigkeiten und die Überprüfung der prognostischen und differenziellen Validität der im Rahmen des Projekts KomMa entwickelten Leistungstests zur Erfassung des professionellen Wissens. Im empirischen Teil der Arbeit wird gezeigt, dass es möglich ist, ein solches videobasiertes Instrument zu entwickeln. In einer quantitativ-empirischen Studie können erste Belege für die prognostische und differenzielle Validität der KomMa-Leistungstests gegeben werden. Bezogen auf das Hauptziel zeigt die Analyse der Daten, dass professionelle Kompetenz frühpädagogischer Fachkräfte im Bereich Mathematik erwartungsgemäß ein mehrdimensionales Konstrukt ist, bei dem insbesondere das fachdidaktische Wissen und anwendungsorientierte Überzeugungen bedeutsam für die Situationswahrnehmung und Handlungsplanung sind. Damit werden im Anschluss an die wenigen bisher vorliegenden Befunde zur professionellen Kompetenz frühpädagogischer Fachkräfte im Bereich Mathematik weitere Hinweise darauf gegeben, dass dies eine spezifische Form pädagogischen Handelns ist, die somit auch entsprechender Aus- und Weiterbildungsangebote bedarf. / In recent years early mathematical education has increasingly become a subject of didactic research. Whether preschool teachers acquire the competence needed to foster early mathematical literacy as part of their professional training or practice has been examined empirically only in the last six years. Up to now there are still some lacks of research which can be identified. The presented cumulative Ph.D. Study is a first step to close these research gaps. The main objective of this work is to analyze the competence structure of prospective preschool teachers taking into account their dispositions and situation specific skills. This entails two more goals, firstly, the development of a videobased assessment to measure situation specific skills, and, secondly, the review of the prognostic and differential validity of the two achievement tests to measure professional knowledge, developed within the KomMa-project. In the empirical part of the paper it is shown that it is possible to develop such a videobased assessment. In a quantitative empirical study first evidence for the prognostic and differential validity of the KomMa achievement tests is given. Concerning the main objective of this Ph.D. project, the professional competence of prospective preschool teachers in the field of mathematics is examined. As expected, it is shown that competence is a multidimensional construct. Especially the mathematics pedagogical content knowledge and the application-oriented beliefs of the prospective preschool teachers are predictive for their perception of situations and planning of actions. Following the current state of research this P.hD. project provides further evidence that professional competence of prospective preschool teachers in the field of mathematics is a specific form of mathematics education, which thus also requires appropriate training and further education opportunities.

Die vorliegende Arbeit ist Teil eines Lehrerfortbildungsprogramms zur Förderung von Selbstwirksamkeit und Selbstbestimmung bei Schülern. Im Fokus dieser Arbeit steht die Untersuchung der Wirksamkeit eines Teilmoduls dieses Projekts, das auf die Förderung sozialer Kompetenzen und des Klassenklimas abzielte. Als zentrale Interventionsstrategien wurden kooperatives Lernen sowie Maßnahmen der Klimaförderung (soziale Regeln, Klimadiagnose) im Rahmen von Workshops an Lehrerkollegien vermittelt. Über einen Zeitraum von drei Jahren setzten die Lehrkräfte diese Maßnahmen in ihrem regulären Unterricht um und dokumentierten ihre Aktivitäten in Logbüchern. Zur Untersuchung der Wirksamkeit der Intervention wurden in der vorliegenden Arbeit 364 Schüler aus acht Interventionsschulen und 198 Schüler aus fünf Kontrollschulen über drei Messzeitpunkte im Hinblick auf die Entwicklung sozialer Kompetenzen und Kompetenzüberzeugungen sowie auf das Klimaerleben untersucht. Der Vergleich der Schülergruppen zeigte in der Interventionsgruppe eine weniger starke Verschlechterung in der Lehrer-Schüler-Beziehung als ein Merkmal des Klassenklimas. Unter Berücksichtigung des von den Lehrern dokumentierten Implementationsausmaßes wurden weitere Effekte der Intervention deutlich. Ein verstärkter Einsatz der Maßnahmen ging mit günstigeren Entwicklungen der sozialen Kompetenzüberzeugungen, der Schüler-Schüler-Beziehungen sowie der Lehrer-Schüler-Beziehungen einher. Die Befunde zeigen die Wichtigkeit der Erfassung von Informationen zur Implementation im Rahmen von Interventionsstudien auf, da Analysen ohne die Berücksichtigung von Implementationsinformationen zu ungenauen Schlussfolgerungen über die Wirksamkeit der Intervention führen können. Gleichzeitig machen die Befunde deutlich, wie anspruchsvoll eine zuverlässige Erfassung der Implementation im Hinblick auf die Konzeption und Umsetzung ist. Zukünftige Forschung sollte auf diesen Aspekt der Evaluation besonderes Augenmerk legen. / A teacher training program was developed to improve students’ self efficacy and self determination that consists out of three units. In this work one of the units concerning social competence and the classroom climate is focused. The core intervention strategies of this unit were cooperative learning as well as strategies to improve the classroom climate (e.g. social rules, climate diagnostics). These strategies were taught in workshops attended by the teacher stuff of the participating schools. The teachers implemented the strategies in their regular classrooms and documented the implementation fidelity by a logbook. The intervention as well as the implementation was evaluated over a period of three years. The treatment efficacy was tested in a longitudinal study (3 assessment points) at 364 students from 8 schools with intervention and 198 students from 5 schools without intervention serving as control group. The targeted criteria in this evaluation were the development of social competence, social competence beliefs and class climate. Comparing the two groups the teacher-student-relationship decreased less drastically in the schools with intervention compared to the control group. Taking the teachers’ documentation of the implementation fidelity into account results indicate that more frequent implementations of the strategies led to better development of the students’ social competence, the teacher-student-relationship as well as student-student-relationship. Therefore, the results impressively demonstrate the relevance to assess the implementation fidelity in intervention trials. Data on implementation fidelity (exposure, adherence) enables more valid conclusions on the intervention’s effectiveness. However, the project revealed difficulties to develop and to apply instruments to assess implementation fidelity, Therefore, in future research instruments for the evaluation of the implementation process have to be focused as well.